Heat Detector for Unfinished Attic

SS does not offer a heat detector. (it's been asked for, but SS doesn't ever let anyone in on what they're working on, or what they may or may not design/produce).

They have a freeze sensor where you can set the high temp (I don't have one and don't know if it would alert with a high temp setting), but I'd guess the temps in your attic would negate it's purpose.

The SS3 temperature sensor requires a low setting (0 minimum) and a high setting (99 maximum)

One could cheat a bit if they wanted to. Wouldn't be UL listed/certified or anything like that but maybe better than nothing if you really must have.

How crafty are you?

Wire a normally-closed thermostatic switch to a door sensor.

A really far out work around might be "gluing" a magnet to a door sensor with beeswax (melting point 146F, give or take) could make a makeshift heat detector. Laugh if you must, LOL. Depending where you are, perhaps 146F might not be enough.

Keep in mind, that if an entry sensor goes off, that is considered an "emergency" which could result in police dispatch.